UCX Memory

Hi ,

We are using Open VMS 7.1 with UCX V4.2 ECO 5 on one of our VAX 4000 server. We are experiencing some high non zero wait value ( UCX show Comm / Mem ) for large buffer but it is not increasing cumilatively like error counts. Neither it is changing dynamically. For example it is staying at say 4502 for One and half hour then suddenly jumping to 4732 and staying there for some hour again coming back to 589 range for two hours... like this.could you please explain how I can use these values to quantify the error? Is this value representing the wait for that particullar instance? Does it get reset at Midnight with other VMS accounting information? Much you could provide information on this topic will be more helpful for me.

Re: UCX Memory

Raj,

the Waits counter value should not 'decrease', except if it overflows.

Compare the Peak buffer values with the permanently allocated ones and consider to increase the permanent values, if the peak values are near or reach the max values. As far as I remember, the maximum values you define, need to be a multiple of the appropriate MIN= values.

Re: UCX Memory

the use of QUOTAs in OpenVMS generally limits the ability of a single instance (process, user, job, session etc.) to deplete a system-wide resource.

In this case in UCX, it limits the TCP message queue size for Receive/Send messages.

If you are seeing UCX MBUF buffer waits, this mean that the UCX kernel needs a packet from a memory buffer and none is available, so it has to wait. This will cause a little bit of delay in your TCPIP communication. If you don't want this to happen and have enough nonpaged pool, you can increase the number of MBUFs available to the UCX kernel.

Increasing the QUOTAs without increasing the underlying buffer space, may even make things worse.

Re: UCX Memory

Raj,

Found this :Before actual transmission, a transmit data operation moves data from the user process space to the large buffer. Until a user process is ready to read data, a receive data operation stores received data in the large buffers.

Is it possible that user processes doing network traffic are on low priority and thus do not get the cpu to receive the packets ?Is it possible that a cpu eater is active from time to time ?

Re: UCX Memory

The default value for the quota in our system is 4096 and max value for small & large buffer is 1000 and 200. are these all denotes the value in Blocks ? If QUOTA is the limit for individual process / user or instance how can it be 4096, greater than Max large buffer which is 200?